Reticulated ceramic foam catalysts for synthesis gas production

Abstract

Reticulated ceramic monolithic catalysts and non-poisoning catalyst supports comprising one or more metal oxides of chromium, cobalt, nickel, an alkaline earth, a rare earth, or another sinterable metal oxide that are active in any of various chemical oxidation reactions are disclosed. Methods of making the new reticulated ceramic structures comprising impregnating an organic foam or other pore-templating material are also disclosed. Processes for the catalytic conversion of light hydrocarbons to products comprising carbon monoxide and hydrogen employing reticulated ceramic catalysts are described.

What is claimed is:  
     
       1. A method of converting a C 1 -C 5  hydrocarbon to a product gas mixture containing CO and H 2 , the process comprising 
       mixing a C 1 -C 5  hydrocarbon-containing feedstock and an oxygen-containing feedstock to provide a reactant gas mixture;  
       contacting said reactant gas mixture with a catalytically effective amount of a catalyst comprising at least one macroporous reticulated ceramic monolith containing chromium oxide; and  
       maintaining catalytic partial oxidation reaction promoting conditions, said monolith prepared by a process comprising calcining in a non-oxidizing atmosphere.  
     
     
       2. The method of  claim 1  wherein said step of maintaining catalytic partial oxidation reaction promoting conditions comprises, during said contacting, maintaining said catalyst structure and said reactant gas mixture at a temperature of about 600-1,100° C. 
     
     
       3. The method of  claim 1  wherein said step of maintaining catalytic partial oxidation reaction promoting conditions comprises, during said contacting, maintaining said catalyst structure and said reactant gas mixture at a pressure of about 100-12,500 kPa. 
     
     
       4. The method of  claim 1  wherein said step of maintaining catalytic partial oxidation reaction promoting conditions comprises passing said reactant gas mixture over said composition at a continuous space velocity of at least about 20,000 to about 100,000,000 NL/kg/h. 
     
     
       5. The method of  claim 4  wherein said step of passing said reactant gas mixture over said catalyst comprises passing said mixture at a gas hourly space velocity of about 50,000 to about 50,000,000 NL/kg/h. 
     
     
       6. The method of  claim 1  wherein said step of maintaining catalytic partial oxidation reaction promoting conditions comprises maintaining a contact time of less than about 10 milliseconds between said reactant gas mixture and said catalyst. 
     
     
       7. The method of  claim 1  wherein said reticulated ceramic monolith further comprises at least one catalytically active metal or metal oxide chosen from the group consisting of cobalt, nickel, manganese, molybdenum, tungsten, tin, rhenium, bismuth, indium and phosphorus, and oxides thereof. 
     
     
       8. The method of  claim 1  wherein said catalyst further comprises least one metal or metal oxide capable of catalyzing an oxidation reaction chosen from the group consisting of chromium, cobalt, nickel, alkaline earth metals, rare earth metals, manganese, molybdenum, tungsten, tin, rhenium, bismuth, indium and phosphorus, and oxides thereof, supported on said reticulated ceramic monolith. 
     
     
       9. The method of  claim 1  wherein said mixing comprises mixing a methane-containing feedstock and an oxygen-containing feedstock to provide a reactant gas mixture feedstock having a carbon:oxygen ratio of about 1.25:1 to about 3.3:1. 
     
     
       10. The method of  claim 1  wherein said oxygen-containing feedstock further comprises steam, CO 2 , or a combination thereof. 
     
     
       11. The method of  claim 1  wherein said mixing comprises mixing a hydrocarbon feedstock and a gas comprising steam and/or CO 2  to provide said reactant gas mixture. 
     
     
       12. The method of  claim 1  wherein said C 1 -C 5  hydrocarbon comprises at least about 50% methane by volume. 
     
     
       13. The method of  claim 1  wherein said C 1 -C 5  hydrocarbon comprises at least about 80% methane by volume. 
     
     
       14. The method of  claim 1  further comprising preheating said reactant gas mixture. 
     
     
       15. The method of  claim 1  wherein said catalyst comprises the product of the process comprising: 
       drying an aqueous solution of at least one metal salt chosen from the group consisting of salts of chromium, cobalt, nickel, manganese, molybdenum, tungsten, tin, rhenium, bismuth, indium and phosphorus to yield a dried active catalyst or catalyst precursor material;  
       calcining said active catalyst or catalyst precursor material to yield a calcined catalyst or catalyst precursor material;  
       sizing said calcined material to yield an active catalyst or catalyst precursor powder comprising particles of predetermined average size;  
       preparing a solution or slurry containing said powder;  
       impregnating a pore-templating material with said solution or slurry;  
       drying said impregnated pore-templating material;  
       calcining said dry impregnated material at a first temperature to produce a green reticulated ceramic;  
       calcining said green reticulated ceramic at a second temperature higher than said first temperature sufficient to produce sintering of said ceramic, such that a catalytically active reticulated ceramic monolith is produced.  
     
     
       16. The method of  claim 1  wherein each said monolith has sufficient mechanical strength to withstand gas pressure up to about 12,500 kPa and temperatures up to about 1200° C., and has sufficient macroporosity to permit a space velocity of reactant and product gases up to at least about 100,000,000 NL/kg/h. 
     
     
       17. The method of  claim 16  wherein each said monolith contains about 65-80 pores per inch. 
     
     
       18. The method of  claim 16  wherein each said monolith has a surface area of about 5-250 m 2 /g. 
     
     
       19. The method of  claim 16  wherein said catalyst comprises an active catalytic component containing at least one sinterable metal or metal oxide chosen from the group consisting of chromium, cobalt, nickel, manganese, molybdenum, tungsten, tin, rhenium, bismuth, indium and phosphorus, alkaline earth metals and rare earth metals, and oxides thereof. 
     
     
       20. The method of  claim 19  wherein said catalyst comprises nickel oxide. 
     
     
       21. The method of  claim 19  wherein said catalyst comprises manganese oxide. 
     
     
       22. The method of  claim 19  wherein said catalyst comprises magnesium oxide. 
     
     
       23. The method of  claim 19  wherein said catalyst comprises cobalt oxide. 
     
     
       24. The method of  claim 19  wherein said catalyst comprises nickel oxide, manganese oxide, and magnesium oxide. 
     
     
       25. The method of  claim 20  wherein said catalyst comprises nickel oxide and cobalt oxide. 
     
     
       26. The method of  claim 15  wherein said solution or slurry comprises at least one sinterable metal oxide capable of catalyzing an oxidation reaction. 
     
     
       27. The method of  claim 26  wherein said at least one sinterable metal oxide is chosen from the group consisting of oxides of chromium, cobalt, nickel, alkaline earth elements and rare earth elements. 
     
     
       28. The method of  claim 15  further comprising maintaining said ceramic in a non-oxidizing atmosphere during said higher temperature calcining. 
     
     
       29. The method of  claim 15  wherein said impregnated material comprises a chromium salt and/or chromium oxide and said second calcining step comprises maintaining said ceramic in a non-oxidizing atmosphere during said calcining, said non-oxidizing atmosphere chosen from the group consisting of a vacuum, a hydrogen gas atmosphere, an inert gas atmosphere, and an atmosphere comprising a combination of hydrogen and at least one inert gas. 
     
     
       30. The method of  claim 15  wherein said step of impregnating a pore-templating material with said powder-metal oxide solution or slurry comprises impregnating an organic polymer foam substrate. 
     
     
       31. The method of  claim 15  wherein said step of calcining said dry impregnated material to yield a ceramic foam precursor is conducted at a temperature of no more than about 1000° C. 
     
     
       32. The method of  claim 15  wherein said step of calcining said ceramic at a second temperature sufficient to produce sintering comprises heating to a temperature of about 1500-1600° C. 
     
     
       33. The method of  claim 15  wherein said step of preparing a solution or slurry comprises including at least one additional component chosen from the group consisting of a dispersant, a binder, and a wetting agent. 
     
     
       34. The method of  claim 15  wherein when said step of preparing a solution or slurry comprises including a chromium-containing compound, and said method further comprises maintaining said ceramic in a non-oxidizing atmosphere during said higher temperature calcining step. 
     
     
       35. The method of  claim 15  wherein said step of sizing said calcined material comprises reducing said active catalyst or catalyst precursor material to particles less than about 325 mesh. 
     
     
       36. The method of  claim 35  wherein said step of sizing said calcined material comprises reducing said active catalyst or catalyst precursor material to about 20-30 mesh particles. 
     
     
       37. The method of  claim 15 , wherein the catalyst comprises a reticulated ceramic foam catalyst. 
     
     
       38. The method of  claim 1 , wherein the catalyst comprises a reticulated ceramic foam catalyst. 
     
     
       39. A method of converting a C 1 -C 5  hydrocarbon to a product gas mixture containing CO and H 2 , the process comprising: 
       contacting a reactant gas mixture comprising a C 1 -C 5  hydrocarbon and an oxygen-containing gas with at least one supported catalyst structure comprising an active catalytic component disposed on a non-poisoning reticulated ceramic support, said active catalytic component comprising at least one metal or metal oxide selected from the group consisting of chromium, cobalt, nickel, manganese, molybdenum, tungsten, tin, rhenium, bismuth, indium, phosphorus, alkaline earth metals, rare earth metals, and oxides thereof, and said support structure comprising magnesium oxide or chromium oxide, wherein said chromium oxide-containing support structure is prepared by a process comprising calcining said support structure under non-oxidizing conditions;  
       during said contacting, maintaining said catalyst structure and said reactant gas mixture at a temperature of about 600-1,100° C.;  
       during said contacting, maintaining said catalyst structure and said reactant gas mixture at a pressure of about 100-12,500 kPa; and  
       passing said reactant gas mixture over said composition at a continuous flow rate of about 20,000 to about 100,000,000 NL/kg/h.  
     
     
       40. The method of  claim 39  wherein said active catalytic component comprises 0.1 wt % Ni x Cr y  Ox and said support comprises a chromium oxide foam, wherein the subscript x is an atomic ratio of 0.2 and the subscript y is an atomic ratio of 0.8. 
     
     
       41. The method of  claim 39  wherein said support comprises cobalt oxide and chromium oxide foam. 
     
     
       42. The method of  claim 39  wherein said active catalytic component comprises 15 wt % of a composition containing 13 wt % Ni (O), 3 wt % Mn(O), 84 wt % Mg(O), and said support comprises NiO—MgO foam. 
     
     
       43. The method of  claim 39  wherein said active catalytic component comprises 6 wt % Ni x Cr y  Ox and said support comprises NiO—MgO foam, wherein the subscript x is an atomic ratio of 0.2 and the subscript y is an atomic ratio of 0.8. 
     
     
       44. The method of  claim 39  wherein said active catalytic component and said non-poisoning reticulated support comprise the same or a different composition.